CN112310639B

CN112310639B - Flat panel antenna including liquid crystal

Info

Publication number: CN112310639B
Application number: CN202010692347.2A
Authority: CN
Inventors: 崔珉瑾; 朴承烈; 赵秀仁; 张来奉
Original assignee: LG Display Co Ltd
Current assignee: LG Display Co Ltd
Priority date: 2019-07-25
Filing date: 2020-07-17
Publication date: 2024-02-27
Anticipated expiration: 2040-07-17
Also published as: JP2021022927A; US11437725B2; KR102670834B1; JP6980861B2; US20210028545A1; KR20210012418A; TWI748562B; TW202105831A; CN112310639A

Abstract

A panel antenna comprising: a first substrate on which a radiation patch and a ground plane are disposed; a second substrate; a liquid crystal layer between the first substrate and the second substrate; and a feed portion adjacent to the second substrate, wherein the ground plane comprises a slit, wherein the feed portion comprises a first spacer, a second spacer, and a feed line between the first spacer and the second spacer, and wherein the thickness of the first substrate is greater than the thickness of the second substrate.

Description

Flat panel antenna including liquid crystal

Cross Reference to Related Applications

The present application claims priority and benefit from korean patent application No. 10-2019-0090098 filed on 25 th 7 th 2019, the entire contents of which are incorporated herein by reference for all purposes as if fully set forth herein.

Technical Field

The present disclosure relates to a panel antenna, and more particularly, to a panel antenna including a liquid crystal.

Background

The antenna converts an electric signal into an electromagnetic wave or an electromagnetic wave propagating in a free space such as the atmosphere into an electric signal, and functions as a medium for transmitting a signal output from a transmission line to the free space.

In general, parameters for measuring antenna performance include directivity D, radiation efficiency η, antenna gain G, coupling loss L, and bandwidth BW. The directivity D is obtained by dividing the intensity of radiation in a specific direction by the intensity of radiation in all directions. The radiation efficiency η is obtained by dividing the power emitted from the antenna by the power supplied to the antenna. The antenna gain G, which represents the ability to radiate power supplied from the transmission line to the antenna in a specific direction, is obtained by multiplying the directivity D by the radiation efficiency η, i.e., g=d×η. The coupling loss L is the amount of reduction in the energy transferred between the individual lines. The bandwidth BW is the frequency range in which the parameters have appropriate values and the antenna is effectively operated.

An antenna having parameters needs to increase the antenna gain G and decrease the coupling loss L compared to the supplied power in order to improve the efficiency of the power transmitted in a specific direction.

Disclosure of Invention

Accordingly, embodiments of the present disclosure are directed to a patch antenna that substantially obviates one or more problems due to limitations and disadvantages of the related art.

An aspect of the present disclosure is to provide a patch antenna capable of increasing antenna gain and bandwidth and reducing coupling loss.

Additional features and aspects will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the inventive concepts provided herein. Other features and aspects of the inventive concept may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as from the appended drawings.

To achieve these and other aspects of the inventive concept, as embodied and broadly described herein, a patch antenna includes: a first substrate on which a radiation patch and a ground plane are disposed; a second substrate; a liquid crystal layer between the first substrate and the second substrate; and a feeding portion adjacent to the second substrate; wherein the ground plane comprises a slit, wherein the feed portion comprises a first spacer, a second spacer and a feed line between the first spacer and the second spacer, and wherein the thickness of the first substrate is greater than the thickness of the second substrate.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the inventive concepts as claimed.

Drawings

The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this application, illustrate embodiments of the disclosure and together with the description serve to explain various principles of the disclosure. In the drawings:

fig. 1A is a perspective view schematically showing the structure of a patch antenna according to an embodiment of the present disclosure, and fig. 1B is an exploded perspective view showing the structure of a patch antenna according to an embodiment of the present disclosure;

fig. 2 is a view showing radiation of electromagnetic waves in a patch antenna according to an embodiment of the present disclosure;

fig. 3 is a view showing an equivalent circuit of a patch antenna according to an embodiment of the present disclosure;

fig. 4A is a table showing antenna gains in a panel antenna and bandwidths corresponding to thicknesses of first substrates according to an embodiment of the present disclosure;

fig. 4B is a view showing a radiation pattern (radiation pattern) when the thickness of the first substrate is 0.2mm in the panel antenna according to the embodiment of the present disclosure, and fig. 4C is a view showing a radiation pattern when the thickness of the first substrate is 0.5 mm;

fig. 5A is a table showing coupling loss corresponding to the thickness of the second substrate in the patch antenna according to the embodiment of the present disclosure;

fig. 5B is a table showing coupling loss when the thickness of the second substrate is formed to correspond to a multiple of the wavelength of the radiated electromagnetic wave in the patch antenna according to the embodiment of the present disclosure;

fig. 6 is a table showing crosstalk corresponding to a distance between a feeding line and a portion of a feeding portion in a panel antenna according to an embodiment of the present disclosure.

Detailed Description

Reference will now be made in detail to exemplary embodiments of the present disclosure that are illustrated in the accompanying drawings.

Fig. 1A is a perspective view schematically illustrating a structure of a patch antenna according to an embodiment of the present disclosure, and fig. 1B is an exploded perspective view illustrating a structure of a patch antenna according to an embodiment of the present disclosure.

In fig. 1A and 1B, a patch antenna 100 according to an embodiment of the present disclosure includes a first substrate 110, a second substrate 120, a liquid crystal layer 130, and a feeding part 140.

The first substrate 110 may have a first thickness H1, and may be a dielectric material of an insulator having a polarity in an electric field.

For example, the first substrate 110 may be a substrate formed of glass having a first dielectric constant ε 1.

A radiating patch 111 and a ground plane 112 may be provided on the first substrate 110. The radiating patch 111 may be disposed at a first surface of the first substrate 110, and the ground plane 112 may be disposed at a second surface of the first substrate 110. For example, the first surface of the first substrate 110 may be an upper surface of the first substrate 110, and the second surface of the first substrate 110 may be a lower surface of the first substrate 110. Accordingly, the radiating patch 111 may be disposed above the first substrate 110, and the ground plane 112 may be disposed below the first substrate 110.

A fringe field may be generated between the radiating patch 111 and the ground plane 112. The electromagnetic field generated between the edge of the radiating patch 111 and the ground plane 112 may be exposed above the radiating patch 111 and may radiate into free space.

The ground plane 112 may include a slit 113 as an opening, and the slit 113 may have a rectangular shape.

When the slit 113 has a rectangular shape, the slit 113 may be formed along the first direction D1. That is, a long side of the slit 113 may be formed along the first direction D1, and a short side of the slit 113 may be formed along the second direction D2 perpendicular to the first direction D1.

Slit 113 acts as an impedance transformer and a parallel LC circuit. The electric field formed by the feeding portion 140 passes through the slit 113 and is transmitted to the radiation patch 111, so that a current may be induced to flow in the radiation patch 111.

The second substrate 120 may have a second thickness H2, and similar to the first substrate 110, may be a dielectric material that has an insulator with a polarity in an electric field.

The second substrate 120 may be a substrate formed of glass or polyimide having a second dielectric constant epsilon 2.

When the second substrate 120 is a substrate formed of glass, the second dielectric constant ε2 of the second substrate 120 may be the same as the first dielectric constant ε1 of the first substrate 110.

A liquid crystal layer 130 may be disposed between the first substrate 110 and the second substrate 120. The liquid crystal layer 130 may include liquid crystal molecules, and an arrangement of the liquid crystal molecules may be changed according to a voltage applied to the liquid crystal layer 130.

The feeding part 140 may include a feeding line 141. The feeding portion 140 may further include a first spacer ap1 and a second spacer ap2, which are spaces where the feeding line 141 is spaced apart from other portions of the power feeding portion 140. The feeding part 140 may be disposed under the second substrate 120. The feeding line 141, the first spacer ap1, and the second spacer ap2 may be arranged along a second direction D2 perpendicularly intersecting the first direction D1. That is, the long sides of the feeding line 141 and the long sides of the first and second spacers ap1 and ap2 may be parallel to the second direction D2.

More specifically, the feed line 141 may have a first width W1 in the first direction D1, and the long sides of the feed line 141 may be arranged along the second direction D2. The feed line 141 may be disposed to cross the radiation patch 111 and the slit 113 when the patch antenna 100 is viewed from the top.

The feeding line 141 generates an electric field according to a voltage supplied from the outside, and the generated electric field passes through the slit 113 and reaches the radiation patch 111, so that a current may be induced to flow in the radiation patch 111. That is, the feed line 141 and the radiating patch 111 may be coupled to thereby transmit energy applied to the feed line 141 into the radiating patch 111.

The first and second spacers ap1 and ap2 may each have a second width W2 in the first direction D1, and long sides of the first and second spacers ap1 and ap2 parallel to the feeding line 141 may be arranged along the second direction D2. The feeding line 141 may be disposed between the first and second spacers ap1 and ap 2.

The arrangement of the liquid crystal molecules included in the liquid crystal layer 130 may be changed by a voltage applied to the ground plane 112 and the feed line 141, and thus, the dielectric constant of the liquid crystal layer 130 may also be changed.

When the dielectric constant of the liquid crystal layer 130 is changed, the phase velocity of the electromagnetic wave is changed, so that the phase of the signal transmitted and received by the panel antenna can be changed.

As described above, the ground plane 112, the feed line 141, and the liquid crystal layer 130 may function as a phase shifter that changes the phase of a signal transmitted and received by the antenna.

Further, a radiation patch 111 and a ground plane 112 are provided on the first substrate 110, and a feed line 141 is provided adjacent to the second substrate 120, so that the patch antenna 100 can be used as a patch antenna.

As shown in fig. 1A and 1B, a patch antenna 100 according to an embodiment of the present disclosure includes one radiation patch 111, one ground plane 112, and one feed line 141 to function as one patch antenna. However, the present disclosure is not limited thereto, and the panel antenna may include two or more radiating patches, two or more ground planes, and two or more feed lines. In this case, the radiation patch, the ground plane, and the feed line corresponding to each other constitute a plurality of patch antennas with the first substrate and the second substrate interposed therebetween, and the plurality of patch antennas form an array antenna. That is, a plurality of radiation patches may be provided at an upper surface of the first substrate, a plurality of ground planes may be provided at a lower surface of the first substrate, and a plurality of feed lines may be provided at a lower surface of the second substrate. The plurality of radiating patches, the plurality of ground planes, and the plurality of feed lines, which correspond to each other and overlap each other, may respectively constitute a plurality of patch antennas.

At this time, the feeding part 140 may further include a power distribution part (not shown) formed of a printed circuit board, and the power distribution part may have a structure of a T-joint power distributor or a wilkinson power distributor.

Fig. 2 is a view showing radiation of electromagnetic waves in a patch antenna according to an embodiment of the present disclosure.

Depending on the resonance phenomenon, the antenna functions by radiating electromagnetic waves or in response to electromagnetic waves transmitted in free space. When the natural frequency of the antenna and the frequency of the electromagnetic wave match each other, a resonance phenomenon occurs. The natural frequency of an antenna may be referred to as a resonant frequency, and the resonance may vary depending on the structure of the antenna.

In a planar antenna according to an embodiment of the present disclosure, both ends of the radiating patch 111 may be terminated with an open circuit to operate as a resonator.

Specifically, the feed line 141 of fig. 1A and 1B may form an electric field according to a voltage applied from the outside, and the electric field formed by the feed line 141 of fig. 1A and 1B may pass through the slit 113 of fig. 1A and 1B and reach the radiation patch 111, so that a current may be induced to flow in the radiation patch 111.

In addition, an electric field E may be generated between the current-inducing radiation patch 111 and the ground plane 112.

At both ends of S1 and S2, fringe fields F1 and F2 formed between the radiation patch 111 and the ground plane 112 may be exposed above the radiation patch 111. The antenna may radiate an electromagnetic field having a resonance frequency by the fringe fields F1 and F2 exposed above the radiating patch 111.

The patch antenna has a length L1 corresponding to the resonant frequency. The length L1 of the panel antenna may be half of the guide wavelength λd in the first substrate 110 corresponding to the resonance frequency.

As shown in fig. 2, since fringe fields F1 and F2, which may be formed at both ends S1 and S2 of the radiation patch 111, increase the effective length of the radiation patch 111, the length L1 of the radiation patch 111 may be shorter than half of the guide wavelength λd in the first substrate 110.

Equation 1 shows an approximation of the length L1 of the radiating patch 111, and the length L1 may be 0.49 times the guide wavelength λd in the first substrate 110. The guided wavelength in a particular dielectric is obtained by dividing the wavelength in free space by the square root of the dielectric constant of the dielectric. Accordingly, the approximate value of the length L1 of the radiation patch 111 may be 0.49 times the value obtained by dividing the wavelength λ in the free space corresponding to the resonance frequency by the square root of the dielectric constant ε 1 of the first substrate 110.

[ equation 1]

Accordingly, since the distance between the two ends S1 and S2 of the radiation patch 111 is close to half wavelength, the phase difference between the fringe field F1 and the fringe field F2 that can be formed at the two ends S1 and S2 of the radiation patch 111 can be about 180 degrees, and the magnitudes of the fringe fields F1 and F2 can be the same.

Fig. 3 is a view showing an equivalent circuit of a patch antenna according to an embodiment of the present disclosure.

The two ends of the radiation patch 111 of fig. 1A, 1B, and 2 may be RC circuits including a resistor Rs1 and a resistor Rs2 connected in parallel with a capacitor Cs1 and a capacitor Cs2, respectively. That is, the first end of the radiating patch is an RC circuit including the resistor Rs1 and the capacitor Cs1 connected in parallel, and the second end of the radiating patch is an RC circuit including the resistor Rs2 and the capacitor Cs2 connected in parallel.

The slit 113 of fig. 1A and 1B may be an impedance transformer T and an LC circuit. The LC circuit may be a parallel LC circuit in which an inductor Ls and a capacitor Cs are connected in parallel.

The inductor Ls and the capacitor Cs of the LC circuit and the impedance transformer T may be connected to an input terminal I corresponding to the feed line 141 in fig. 1A and 1B.

When a voltage is applied to the input terminal I, the LC circuit resonates according to a first resonant frequency f1, which is changed by the impedance transformer T and transmits the voltage resonating according to a second resonant frequency f2 to the RC circuit.

At this time, the capacitors Cs1 and Cs2 of the RC circuit form the fringe fields F1 and F2 of fig. 2, so that electromagnetic waves can be radiated at both ends of the radiation patch 111 of fig. 1A, 1B, and 2.

Using this principle, a patch antenna according to an embodiment of the present disclosure may radiate electromagnetic waves. In addition, the antenna gain G and the bandwidth BW may be increased and the coupling loss L may be reduced by using the first substrate 110 of fig. 1A and 1B and the second substrate 120 of fig. 1A and 1B. This will be described hereinafter.

Fig. 4A is a table showing antenna gains in a panel antenna and bandwidths corresponding to the thickness of a first substrate according to an embodiment of the present disclosure.

The first substrate 110 of fig. 1A and 1B included in the patch antenna according to the embodiment of the present disclosure may be a dielectric.

As the thickness of the dielectric increases, the wavelength of electromagnetic waves emitted from the antenna increases, so that the resonant frequency may decrease.

In addition, as the thickness of the dielectric increases, the magnitude of the leaked electric field may increase, and thus the quality factor, i.e., Q factor at resonance, may decrease.

Since the bandwidth BW increases as the Q factor decreases, electromagnetic waves in a broadband may be emitted as the thickness of the first substrate 110 of fig. 1A and 1B, which is a dielectric, increases.

In fig. 4A, the bandwidth BW shown according to the first thickness H1 of the first substrate 110 of fig. 1A and 1B is increased from 0.2mm to 0.7 mm by 0.1 mm. It can be seen that as the first thickness H1 increases, the bandwidth BW increases from 640MHz to 760MHz. In addition, it can be seen that as the first thickness H1 increases, the resonant frequency f decreases from 11.62GHz to 10.68GHz.

In particular, since the bandwidth BW is maximized to 780MHz when the first thickness H1 is 0.5mm, the first thickness H1 of the first substrate 110 of fig. 1A and 1B may be preferably 0.5mm in order to use an antenna in a broadband.

As the thickness of the dielectric increases and the magnitude of the leaked electric field increases, the radiation power may increase, and as the radiation power increases, the antenna gain G may increase. The antenna gain G may thus increase as the thickness of the first substrate 110 of fig. 1A and 1B increases, the first substrate 110 being a dielectric.

In fig. 4A, the antenna gain G shown according to the first thickness H1 of the first substrate 110 of fig. 1A and 1B is increased from 0.2mm to 0.7 mm by 0.1 mm. It can be seen that as the first thickness H1 increases, the antenna gain G increases from 1.98dBi to 3.03dBi.

In particular, since the antenna gain G is maximized to 3.35dBi when the first thickness H1 is 0.5mm, the first thickness H1 of the first substrate 110 of fig. 1A and 1B may be preferably 0.5mm in order to improve the radiation efficiency of the antenna.

Fig. 4B is a view showing a radiation pattern when the thickness of the first substrate is 0.2mm in the panel antenna according to the embodiment of the present disclosure, and fig. 4C is a view showing a radiation pattern when the thickness of the first substrate is 0.5mm.

In fig. 4B, when the first thickness H1 of the first substrate 110 of fig. 1A and 1B is 0.2mm, the color of the radiation pattern on the horizontal line is close to yellow, and the antenna gain G is from-5.0 dB to-2.5 dB.

On the other hand, when the first thickness H1 of the first substrate 110 of fig. 1A and 1B is 0.5mm, the color of the radiation pattern on the horizontal line is close to orange, and the antenna gain G is-2.5 dB to 0dB. It can be seen that the antenna gain G at the first thickness H1 of 0.5mm increases compared to the case where the first thickness H1 is 0.2mm.

As described above, in the patch antenna according to the embodiment of the present disclosure, when the first thickness H1 of the first substrate 110 of fig. 1A and 1B is increased, the bandwidth BW and the antenna gain G, which are preferably at 0.5mm, may be maximized.

Fig. 5A is a table showing coupling loss corresponding to the thickness of the second substrate in the panel antenna according to the embodiment of the present disclosure.

The feed lines 141 of fig. 1A and 1B attached to the lower face of the second substrate 120 of fig. 1A and 1B form an electric field according to a voltage applied from the outside, and the electric field passes through the slits 113 of fig. 1A and 1B and reaches the radiation patch 111 of fig. 1A and 1B, so that a current may be induced to flow in the radiation patch 111 of fig. 1A and 1B.

As the distance between the feed line 141 of fig. 1A and 1B and the radiation patch 111 of fig. 1A and 1B increases, the magnitude of the radiation electric field reaching and affecting the radiation patch 111 of fig. 1A and 1B decreases, so that the coupling loss L may increase.

Accordingly, the coupling loss L may increase as the thickness of the second substrate 120 of fig. 1A and 1B increases, and the second substrate 120 may be disposed between the feeding line 141 of fig. 1A and 1B and the radiation patch 111 of fig. 1A and 1B.

In fig. 5A, a coupling loss L of 0.1 mm in increments of 0.1 mm from 0.1 mm to 0.5mm at resonance frequencies of 11GHz, 11.5GHz, and 12GHz according to the second thickness H2 of the second substrate 120 of fig. 1A and 1B is shown. When comparing the average resonant frequencies, it can be seen that the average coupling loss L increases with increasing second thickness H2 and decreases from-5.56 dB to-1.77 dB with decreasing second thickness H2.

In particular, since the average coupling loss L is minimized to-1.32 dB when the second thickness H2 is 0.2mm, the second thickness H2 of the second substrate 120 of fig. 1A and 1B may preferably be 0.2mm in order to improve transmission efficiency when fed from the feed line 141 of fig. 1A and 1B to the radiation patch 111 of fig. 1A and 1B.

Fig. 5B is a table showing coupling loss when the thickness of the second substrate is formed to correspond to a plurality of wavelengths of the radiated electromagnetic wave in the patch antenna according to the embodiment of the present disclosure.

In the table of fig. 5B, the second thickness H2 of the second substrate is divided into four bands, and the coupling loss L is shown to correspond to the four bands.

When the wavelength λ of the radiated electromagnetic wave is 27300 μm, the coupling loss L is-1.5705 dB in the case where the second thickness H2 of the second substrate 120 of fig. 1A and 1B is between 0.018 and 0.026 times the wavelength λ. On the other hand, in the case where the band of the second thickness H2 is reduced and is between 0.007 and 0.015 times the wavelength λ, the coupling loss L is minimized to-1.0624 dB.

However, it can be seen that when the second thickness H2 is less than 0.007 times the wavelength λ, the coupling loss L increases to-1.6247 dB.

When the wavelength λ of the radiated electromagnetic wave is 26100 μm, the coupling loss L is-1.8157 dB in the case where the second thickness H2 of the second substrate 120 of fig. 1A and 1B is between 0.019 times and 0.027 times the wavelength λ. On the other hand, in the case where the band of the second thickness H2 is reduced and is between 0.008 times and 0.015 times the wavelength λ, the coupling loss L is minimized to-0.6959 dB.

However, it can be seen that when the second thickness H2 is less than 0.008 times the wavelength λ, the coupling loss L increases to-0.8299 dB.

When the wavelength λ of the radiated electromagnetic wave is 25000 μm, the coupling loss L is-13.3117 dB in the case where the second thickness H2 of the second substrate 120 of fig. 1A and 1B is between 0.020 and 0.028 times the wavelength λ. On the other hand, in the case where the band of the second thickness H2 is reduced and is between 0.008 times and 0.016 times the wavelength λ, the coupling loss L is minimized to-0.6987 dB.

However, it can be seen that when the second thickness H2 is less than 0.008 times the wavelength λ, the coupling loss L increases to-0.9106 dB.

In fig. 5B, it can be seen that when the band of the second thickness H2 of the second substrate is highest (0.018 λ to 0.026λ,0.019 λ to 0.027λ,0.020 λ to 0.028λ) and lowest (0.007 λ, 0.008 λ), the coupling loss L increases, and the coupling loss L decreases in the band between the highest and the lowest.

This is because, if the second thickness H2 of the second substrate 120 of fig. 1A and 1B increases, the distance between the feeding line 141 of fig. 1A and 1B and the radiation patch 111 of fig. 1A and 1B increases, and the magnitude of the radiation electric field reaching and affecting the radiation patch 111 of fig. 1A and 1B may decrease. In addition, this is because, if the second thickness H2 of the second substrate 120 of fig. 1A and 1B is less than a certain range, an electric field formed from the feed line 141 of fig. 1A and 1B and reaching the radiation patch 111 of fig. 1A and 1B may be affected by the ground plane 112 of fig. 1A and 1B, and the coupling loss L may increase.

Therefore, when the second thickness H2 of the second substrate 120 of fig. 1A and 1B is between 0.008 times and 0.018 times, the coupling loss may be minimized, the 0.008 times being the maximum value when the band in fig. 5B is the lowest, and the 0.018 times being the minimum value when the band in fig. 5B is the highest.

As described above, in the embodiments of the present disclosure, the entire thickness of the antenna may be kept constant by increasing the first thickness H1 of the first substrate 110 of fig. 1A and 1B or decreasing the second thickness H2 of the second substrate 120 of fig. 1A and 1B. In this case, the antenna may be formed in a symmetrical shape in which the thickness of the first substrate 110 of fig. 1A and 1B is greater than the thickness of the second substrate 120 of fig. 1A and 1B.

The feed line 141 of fig. 1A and 1B and the radiating patch 111 of fig. 1A and 1B may not be connected and form separate lines, and may be coupled by transmitting energy to each other.

However, the feed line 141 of fig. 1A and 1B may not be coupled with the radiation patch 111 of fig. 1A and 1B, and may be coupled with other components to thereby generate crosstalk. Cross-talk results in reduced efficiency with respect to the antenna.

In the panel antenna according to the embodiment of the present disclosure, the first spacer ap1 of fig. 1A and 1B and the second spacer ap2 of fig. 1A and 1B may be included, and the feed line 141 of fig. 1A and 1B may be spaced apart from other components having conductive characteristics, so that crosstalk may be reduced.

In fig. 6, crosstalk for each of the resonance frequencies 11GHz, 11.5GHz, and 12GHz is shown. It can be seen that when the resonance frequency is 11GHz, in the case where the second width W2 of the first spacer ap1 of fig. 1A and 1B and the second spacer ap2 of fig. 1A and 1B is greater than or equal to twice the first width W1 of the feed line 141 of fig. 1A and 1B, the crosstalk is-1.0624 dB or-1.0684 dB, and in the case where the second width W2 is less than twice the first width W1, the crosstalk is-1.0749 dB. That is, in the case where the second width W2 is smaller than twice the first width W1, crosstalk increases. These characteristics are the same when the resonance frequencies are 11.5GHz and 12 GHz.

Accordingly, in order to minimize crosstalk, the second width W2 of the first and second spacers ap1 and ap2 of fig. 1A and 1B may be twice or more than the first width W1 of the feed line 141 of fig. 1A and 1B.

As described above, in the planar antenna of the present disclosure, the radiation patch and the ground plane having the slit are provided on the first substrate, the second substrate includes the feed line, and the first substrate and the second substrate have different thicknesses, so that the antenna gain and bandwidth can be improved, and the coupling loss can be reduced.

In addition, crosstalk can be reduced by forming a distance of twice or more the width of the feeding line between the feeding line and a portion of the feeding section.

It will be apparent to those skilled in the art that various modifications and variations can be made in the antenna of the present disclosure without departing from the technical spirit or scope of the disclosure. Accordingly, it is intended that the present disclosure cover the modifications and variations of this disclosure provided they come within the scope of the appended claims and their equivalents.

Claims

1. A panel antenna comprising:

a first substrate on which a radiation patch and a ground plane are disposed;

a second substrate;

a liquid crystal layer between the first substrate and the second substrate; and

a feeding portion adjacent to the second substrate,

wherein the ground plane comprises a slit,

wherein the feeding portion includes a first spacing portion, a second spacing portion, and a feeding line between the first spacing portion and the second spacing portion,

wherein the thickness of the first substrate is greater than the thickness of the second substrate, an

Wherein the second substrate is disposed between the liquid crystal layer and the feeding portion.

2. The panel antenna of claim 1, wherein the first and second substrates are made of glass and have the same dielectric constant.

3. The panel antenna of claim 1, wherein the first substrate has a thickness of 0.5mm.

4. A panel antenna according to claim 3, wherein the thickness of the second substrate is 0.2mm.

5. The panel antenna of claim 1, wherein the second substrate has a thickness of 0.008 to 0.018 times a wavelength corresponding to a resonant frequency of the antenna.

6. The panel antenna of claim 1, wherein the first substrate is made of glass and the second substrate is made of polyimide.

7. The panel antenna of claim 1, wherein the slit is formed along a first direction, and

wherein the feed line, the first spacer and the second spacer are arranged along a second direction intersecting the first direction.

8. The panel antenna according to claim 1, wherein the widths of the first and second spacers are twice or more the width of the feed line.

9. The panel antenna according to claim 1, wherein an arrangement of liquid crystal molecules included in the liquid crystal layer can be changed by a voltage applied to the ground plane and the feed line.

10. The panel antenna of claim 1, wherein two fringe fields are formed at both ends of the radiating patch, and wherein a phase difference between the two fringe fields is 180 degrees, and the two fringe fields are the same size.

11. A panel antenna comprising:

a first substrate and a second substrate facing each other and having different thicknesses;

a radiating patch disposed on a first side of the first substrate;

a ground plane disposed on a second side of the first substrate and having a slit extending in a first direction;

a feeding portion attached to the second substrate and including a first spacer, a second spacer, and a feeding line between the first spacer and the second spacer,

wherein the feed line and the radiating patch are electrically coupled with a voltage supplied to the feed line and transferred to the radiating patch, an